Association between functional polymorphism in EGF 61 G/A gene and malignant melanoma
Malignant melanoma, the most serious cutaneous malignancy, has attracted substantial attention because of its rapidly increasing incidence and the poor prognosis of some tumours. Little is known of the genetic factors that mediate susceptibility to, and outcome of, sporadic malignant melanoma. Because of its role in mitogenesis, which is especially relevant to wound healing, tumorigenesis, and proliferation of epidermal tissues, epidermal growth factor (EGF) is an attractive candidate in which to look for genetic polymorphisms. We enrolled 135 white European patients with malignant melanoma and 99 healthy white European controls, and screened a selection of DNA samples for polymorphisms in the promoter and 5' untranslated region of the EGF gene by analysis. We then screened DNA samples from all participants for the identified polymorphism by restriction-fragment-length polymorphism (RFLP) analysis. In-vitro EGF production was measured in peripheral-blood mononuclear cells from 34 controls, and the results were compared with the individuals' EGF genotypes. We identified a single nucleotide substitution (G to A) at position 61 of the EGF gene. Allele frequencies in the controls were 56% EGF 61*A and 44% EGF 61*G. Cells from individuals homozygous for the 61*A allele produced significantly less EGF than cells from 61*G homozygotes (p=0.0004) or heterozygous A/G individuals (p=0.001). Compared with the A/A genotype, G/G was significantly associated with Breslow thickness (p=0.045) and with risk of malignant melanoma (odds ratio 4.9 [95% CI 2.3-10.2], p<0.0001). This study suggests that high EGF production might be important in the development of malignant melanoma.